This invention relates to a polymeric candle composition and candles manufactured from the polymeric candle composition.
Candles have been used by mankind for centuries. There are various types of candles. A common type of candles that sees widespread use consists of a wick embedded in predominantly a block of paraffin wax which provides the fuel for burning the candle. The paraffin wax used in candles typically is highly refined and crystalline at room temperature. Crystalline paraffin is naturally white. Therefore, candles made from crystalline paraffin wax generally are opaque.
In addition to opaque candles, some transparent or clear candles have become available. For example, transparent candles may be made from a composition that includes a thermoplastic polyamide resin and a flammable solvent which is capable of solubilizing the resin at temperatures below about 212xc2x0 F. The flammable solvent also is capable of forming a transparent-gel type structure with the resin. The flammable solvent may be selected from unsaturated fatty acids, unsaturated fatty alcohols, saturated fatty alcohols, esters of fatty acids with polyhydric alcohols and glycerol, and mixtures thereof Other transparent gel formulations also have been developed over the past decades.
While the burning of a candle might appear to be simple and uninvolved, the process that takes place in the burning of a candle imposes rather stringent requirements upon the candle body material. For instance, the candle body should be rigid enough to support itself or be supported in a container; but it should not be excessively brittle at low room temperatures. During burning, the heat of the candle flame melts a small pool of the candle body material around the base of the exposed portion of the wick. This molten material is drawn up through and along the wick by capillary action to fuel the flame. The melting point of a candle material generally is important because the candle material should liquefy at or below temperatures to which the candle material can be raised by radiant heat from the candle flame. If the melting temperature of the candle is too low, the candle will drip or, in an extreme case, the entire candle body will melt, dropping the wick into a pool of molten candle body material, with the potential that the surface of the pool could ignite. On the other hand, if the melting point is too high, the flame will be starved because insufficient fuel will be drawn up through the wick with the result that the flame will be too small to maintain itself. When molten, the candle body material preferably should have a relatively low viscosity to ensure that it will be capable of being drawn up through the wick by capillary action. Moreover, it is preferred that the candle body material burn with a flame that is both luminous and smokeless. The odors that are produced by the combustion should not be unpleasant or intrusive.
Due to these considerations and requirements, most candle compositions generally have been limited to wax-based candles which are opaque. Although a number of transparent candles are available, candles capable of changing from opaque to substantially transparent while lit are largely unknown. Such candles would be desirable because they are aesthetically appealing and provide an alternative to the existing candles. Therefore, there is a need to explore methods to make a candle which is substantially opaque at room temperature, but turns substantially transparent when lit.
The invention meets the above need by providing a polymeric candle which is substantially opaque at room temperature; but at least a portion of the polymeric candle turns substantially transparent after it is lit. The polymeric candle is formed from a candle composition which includes a wax and a polymeric material. The wax and polymeric material are selected such that the polymeric candle composition has a phase transition temperature of about 35xc2x0 C. or higher. The resulting composition is substantially opaque at a temperature below the phase transition temperature, and at least a portion of the composition becomes substantially transparent at or above the phase transition temperature. The candle composition may further include a hydrocarbon oil or mixtures thereof Preferably, the wax is a paraffin wax with at least 20 carbon atoms per molecule. The preferred polymeric material is a block copolymer that includes at least two blocks: a rigid block and an elastomeric block. Additional aspects of the invention, objects and advantages of embodiments of the invention are further described in the following.